Re: RFC: i386: kill !4KSTACKS

[Mark Lord]

Daniel Phillips wrote:
> There are only two stacks involved, the normal kernel stack and your new ndis 
> stack.  You save ESP of the kernel stack at the base of the ndis stack.  When 
> the Windows code calls your api, you get the ndis ESP, load the kernel ESP 
> from the base of the ndis stack, push the ndis ESP so you can get back to the 
> ndis code later, and continue on your merry way.

With CONFIG_PREEMPT, this will still cause trouble due to lack
of "current" task info on the NDIS stack.

One option is to copy (duplicate) the bottom-of-stack info when
switching to the NDIS stack.

Another option is to stick a Mutex around any use of the NDIS stack
when calling into the foreign driver (might be done like this already??),
which will prevent PREEMPTion during the call.

Cheers
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